1. Field of the Invention
The present invention relates to a multi-layered film preparation for pain-killing and protecting an affected part of mucous membrane in the oral cavity and more particularly, to that improved in handling thereof.
2. Related Arts
Hitherto, many proposals have been made on a preparation to be applied on an affected part in mucous membrane, and more particularly to that in oral cavity.
As an adhesive preparation was disclosed in Jap. Pat. No. 54-41320 (A) which comprises a compact mixture or composition to be adhered on mucous membrane in the oral cavity and containing hydroxypropylcellulose, polyacrylic acid or a salt thereof as well as a drug or effective ingredient agent. This preparation has been formed by tabletting granular or powderform ingredients, has thickness of 1 mm or more, and is poor in flexibility. Therefore, such a preparation gives a certain malaise to a patient, when it has been adhered on mucous membrane in the oral cavity, and possibly causes a pain.
For improving such a feeling in use and sustaining power in effect, then, it has been studied on various film preparations having a layer difficult to dissolve in water (non-adhesive layer), as disclosed in Jap. Pat. Nos. 63-18923(B), 58-128314(A), 58-213709(A), 2-60644(B), and 62-56420(A).
These film preparations solve the feeling in use and sustaining power in effect, but shows such a disadvantage that a force of adhesion becomes low, as a degree of moisture in the area of mucous membrane (affected part) is higher. In order to dissolve the problem, investigations have been made on various adhesive base materials and a combination thereof, as disclosed in Jap. Pat. Nos. 62-135417(A), 3-33215(B), 6-2669(B), 6-2670(B), 3-246220(A), and 4-266819(A). An amount of the adhesive base material to be composed has also been investigated, but a preparation improved in both of the adhesive force and feeling in use has not yet been developed, since the feeling in use becomes worth due to stickiness, as the amount thereof increases.
A double-layered film preparation consisting of a drug containing layer and non-water soluble layer (non-adhesive layer) has been investigated, since in case of applying an adhesive preparation to an affected part in narrow space as in a oral cavity, the preparation tends to stick to fingers, or slips-off from the affected part. Moreover, triple-layered preparation having an an adhesive layer in addition to said layers, It has also been investigated in order to increase the force of adhesion to mucous membrane in the oral cavity. Such a preparations shows a sufficient force of adhesion, if moisture of the mucous membrane in oral cavity is not so high as in a healthy person, but does not show the sufficient force of adhesion, when an affected part is in highly moist state due to an erosion caused by an infectional disease or side effect through a radiotherapy and/or chemotherapy, so that falling out from the affected part or getting out of its position due to slipping can not be prevented.